Apparatus for separating liquids of different specific gravities



APPARATUS POR SEPARATING LIQUIDs oP DIFFERENT SPECIFIC GRAVIIIES Aug, 9, 1932. A s. A. B. DIM-u caPeENv Original Filed June 2l. 1950 www@ F TNB fen 5y 7 Patented Aug. 9, 1'932 UNITED STATES PATENT OFFICE SVEN ALFRED BERTIL DAHLGREN, OF ALSTEN, SWEDEN, ASSIGNOR TO THE DE LAVAL SEPARATOR COMPANY, OF NEW' YORK, N. Y., A CORPORATION OF NEW JERSEY APPARATUS FOR SEPARATIITG LIQUIDS 0F DIFFERENT SPECIFIC GRAVITIES Original application led June 21, 1930, Serial No. 462,773, and in- Sweden July 3, 1929. Divided and this application led April 28, 1931.

In separating two liquids of different specific gravities, for instance oil and water, it is generally possible to obtain continuous discharge of the liquids by arranging a liquid seal of the heavier liquid in the separating vessel. If the separation takes place in a centrifuge and if a mixture of the two liquids is fed into the bowl of the centrifugez the heavier liquid will be separated out towards the periphery of the bowl, where it displaces a corresponding quantity of liquid via the liquid seal, said liquid leaving the bowl through an outlet at a certain distance from the axis of rotation of the bowl. The lighter liquid moves inwards towards the centre and is discharged from the bowl at a smaller distance from the axis of rotation of the bowl. To attain the highest separating eiiiciency, the outlet radius should be such that the level between the lighter and the heavier liquid in the centrifugal bowl is at the greatest possible diameter. If the liquids contain solid impurities, which must be separated out, the correct determination of said outlet radius is of the greatest importance for the result of the separation, as these impurities generally are more diiiicult to separate than the liquids and also interfere with the separation of the liquids.

To obtain in every case the most advantageous position of the level in the bowl according to the specific gravities of the liquids, the outlets for liquid have been arranged in such manner that their distance from the axis of rotation of the bowl can be varied. A

common :method is to take out one of the liquids through a ring that is concentric with the axis of rotation of the bowl, said ring being replaceable by a similar ring of any desired different inner diameter. Another method is to move the outlet radius of the heavier or the lighter liquid in a radial direction by means of a screw.

The regulation brought about by exchange of rings or by adjustment of screws involves Serial No. 533,428.

great inconveniences, especially as the speciiic gravities of the liquids often vary. It may even happen that the specific gravities of the liquids vary during the separation. This is for instance the case when separating ing the press-liquid obtained from olives. `Whereas the specific gravity of the olive oil is comparatively constant, the specific gravity of the fruit water may vary between 1.00 and 1.12. At the same time a very exact adjustment of the bowl is of the utmost importance for the result of the separation, making it necessary often to stop the separator so that the levels can be regulated. In unfavorable cases such a regulation of the levels may be necessary several times an hour, so that the centrifuge works in an uneconomical manner and is troublesome to operate.

The obj-ect of the present invention is to avoid the necessity of manual regulation of either of the liquid outlets or of stoppage of the centrifuge in order to maintain the conditions required to efficient separation. The object of the invention is attained by means of a novel construction of centrifuge wherein is maintained a constant level between the two liquids in the separating chamber independent of the specific gravities of the liquids. A preferred embodiment of the invention is shown in the accompanying drawing, wherein- Fig. 1 is a diagram illustrating a decanting apparatus wherein separation is effected by gravity, such decanting apparatus and its descripton aiding in understanding the prineiple governing the operation of the centrifuge.

Fig. 2 is a vertical section through a centrifuge embodying my invention.

Fig. 3 is a plan view of the central feed tube, the initial lighter liquid outflow channel and the upper surface of the plate forming the bottom of the auxiliary separating chamber.

Fig. 4 is a detail sectional view of means for regulating the radius of the outlet from the outflow passage of' once-separated lighter liquid.

In order to illustrate the principle of operl ation of the centrifuge, it will be assumed that the separation is taking place under the influence of gravity instead of under centrifugal force, and :for this purpose reference will first be made to Fig. l.

The mixture of liquids, consisting of, for instance, oil and water, is fed into the separating vessel through the inlet A. In the chamber B separation takes place, the water and the impurities sinking to the bottom of the vessel and the lighter oil rising to the surface. The water discharges through the fixed outlet C through a water seal. is static equilibrium between the column of water D and the column of oil E. The purified oil discharges at F through the tube G, which extends down to about, but not necessarily exactly, the level at which one desires to keep the boundary level between the two liquids in the separating vessel. Through the tube G the oil is led into a chamber R in which the oil must pass through a layer.

it again meets the water in the chamber Ry and the water has also been liberated from solid impurities, so that the liquids easily effect a clean separation.

If now the specific gravity of the water suddenly increases, the weight of the column of water D also increases. In order that there shall be equilibrium between said column of water and the column of liquid under the fixed oil outlet I, the height of the column of water H must be such that the pressure of the same plus the pressure of the column of oil over it is equal to the pressure of the col umn of water D. In order that the oil shall be able to surmount the increased pressure of the water, it is necesary that the height of the column of oil E shall increase simultaneously. The level between water and oil in the separating vessel will still be at the same height, water and oil discharge at fixed levels, and the only result of the variation in the specific gravity of the water is that 'the height ofthe column of oil E automatically increases or decreases.

Figs. 2 and 3 show a centrifugal bowl embodying my invention and adapted to carry out the process in accordance with the principle shown in Fig. l and above described. The vmixture of liquids is fed into the bowl through the central feed tube A and is introduced into the separating chamber B through the channels K and L. The heavier liquid as well as the solid impurities move towards the wall of the bowl under the influence of the centrifugal force. The former discharges continuously through the channels M to the Therer fixed outlet C', whereas the heavier solid impurities that are not carried out with the liquid deposit on' the wall of the bowl. The lighter liquid moves inwards to the center of the bowl and is gradually liberated from the heavier liquid and the impurities. The bowl shown in the figure is fitted with a pile of discs, the object of the same being to increase the separating efficiency of the bowl. The purified oil flows outwards through the holes F and the channels G and surmounts the pressure of the heavier liquid in the chamber R, which is connected with the liquid seal by means of the channels T, and then returns inwards to the center at the side of or yover the channels G', and finally discharges through the fixed oil outlet I. The eiciency of the separation in the chamber R can be increased by letting the lighter liquid also pass through a pile of discs in this chamber. The level N in the bowl between the heavier and the lighter liquid keeps at a constant distance from the axis of rotation of the bowl if the specific gravity of either of the liquids should vary, analogous to what is the case gith the static separating tank illustrated in By lengthening or shortenin the tubes G at their outer ends, it is possib e to move the level between the liquids from orv towards the center of the bowl respectively. The level for the discharge of the oil in the chamber R and thus also the level between the liquids @Can be made variable by means of special regulating devices, for instance, by means of In certain cases, as, for instance, when the specific gravities he close to each other and `undergo but small changes during the separation, it may be desirable to place the outlets for the liquids at as small a diameter as possible, one advantage of this being reduced power consumption for the separation. It is also suitable to provide regulating devices for the variation of the diameter of outlets for the liquids, said regulating devices having, however, uo influence on the position of the level between the twor liquids in the centrifugal bowl.

The separation of oil and water and of olive oil and fruit water are merely examples of mixed liquids capable of separation in my improved centrifuge. It should be understood that the centrifuge is capable of use with all mixtures of liquids which are capable of being centrifugally separated.

From the foregoing description it is clear that the centrifuge described is adapted to carry out a new process of separating liquids of different specific gravities. No claim is made herein to such process, Whose execution is not dependent on the employment of any particular apparatus. Such process forms the subject-matter of an application iiled llune 21, 1930, Serial No. 462,773, of which this application is a division.

Having now fully described my invention, what 1 claim and desire to protect by Letters Patent is:

1. A centrifugal bowl comprising a main separating chamber, a heavier liquid discharge channel extending inward from the peripheral part of the bowl and arranged to provide a heavier liquid seal between the separating space of the bowl and the outlet from said discharge channel, an auxiliary separating chamber adapted to receive separated heavier liquid, a lighter liquid outflow channel extending outward Jfrom the central part of the bowl to said auxiliary chamber, and a lighter liquid discharge conduit extending inward from said auxiliary chamber.

2. A centrifugal bowl comprising a main separating chamber, a heavier liquid discharge channel extending inward from the peripheral part of the bowl and arranged to provide a heavier liquid seal between the separating space of the bowl and the outlet from said discharge passage, an auxiliary separating chamber communicating with said liquid seal and adapted to receive therefrom separated heavier liquid, a lighter liquid outflow channel extending outward from the central part of the bowl to said auxiliary separating chamber, and a lighter liquid discharge conduit extending inward from said auxiliary separating chamber, the outlet from the heavier liquid discharge channel being at a. greater distance from the axis of the bowl than the outlet from the lighter liquid discharge conduit and the outlet from the lighter liquid discharge conduit being at a greater distance from the axis of the bowl than the inlet to the lighter liquid outiiow channel.

3. A centrifugal bowl comprising a main separating chamber, a. heavier liquid discharge channel extending inward from the peripheral part of the bowl and arranged to provide a heavier liquid seal between the separating space of the bowl and the outlet from said discharge passage, an auxiliary separating chamber adapted to receive separated heavier liquid, a lighter liquid outflow chan nel extending outward from the central part of the bowl to said auxiliary chamber, a lighter liquid discharge conduit extending inward from said auxiliary chamber, and means to adjust the outlet from said lighter liquid outflow channel to different radia.

4. A centrifugal bowl comprising a main separat-ing chamber, an auxiliary separating chamber arranged relatively close to but spaced Jfrom the periphery of the bowl, a heavier liquid discharge channel communicating with the peripheral part of the bowl outside said auxiliary separating chamber, there being a fluid connection between the auxiliary separating chamber and that part of the heavier liquid discharge channel outside said auxiliary separating chamber, a lighter liquid outflow channel extending outward Jfrom the central part of the bowl to said auxiliary separating chamber, and means to discharge re-separated lighter liquid from said auxiliary separating chamber.

in testimony of which invention, I have hereunto set my hand, at Stockholm, Sweden, on this 8th day of April, 1931.

SVEN ALFRED BERTII. DAHLGREN. 

